Impact of shift work on dementia: a systematic review and dose-response meta-analysis

OBJECTIVES

Although shift work has been reported as having a link to dementia, evidence remains inconsistent, and a comprehensive dose-response meta-analysis of the association is still lacking. We therefore conducted this meta-analysis to explore the association between shift work and the risk of dementia.

STUDY DESIGN

Systematic review and dose-response meta-analysis.

METHODS

PubMed, Embase, and Web of Science databases were systematically searched. Fixed or random-effects models were used to estimate the summary relative risks (RRs) and 95% confidence intervals (95% CIs). Generalized least squares regression was used to estimate dose-response associations, and restricted cubic splines were used to examine possible linear or non-linear associations.

RESULTS

Five articles (10 studies) with 72,999 participants and 23,067 cases were eventually included in the meta-analysis. The summary RRs and 95% CIs of dementia risk with shift work and night shift work versus daytime work were 1.13 (95% CI: 1.05-1.21, I2 = 46.70%) and 1.13 (95% CI: 1.03-1.24, I2 = 9.20%), respectively. The risk of dementia increased by 1% (RR = 1.01, 95% CI: 1.01-1.02, I2 = 41.3%) with each 1-year increase in the duration of shift work. We found a non-linear dose-response association between the duration of shift work and the risk of dementia (Pnon-linearity = 0.006). Though the shape of the curve was steeper with the duration of shift work <7 years, the increase was more gradual after 7 years.

CONCLUSION

Our findings suggest that shift work may be a risk factor for future dementia and that controlling the length of shift work is a feasible measure that may contribute to prevent dementia.

Potential role of circulating exosome miRNAs in left ventricular remodeling of patients with ST-segment elevation myocardial infarction

Background

Left ventricular remodeling (LVR) in patients with ST-segment elevation myocardial infarction (STEMI) may lead to poor prognosis in which circulating exosome miRNAs play a critical role. The aim of the present study is to identify specific exosome miRNAs for LVR in patients with STEMI.

Method

Plasma exosome miRNAs were assessed in 20 patients (90% male, mean age of 66.95±1.65 years) 3–6 months after STEMI and 24 healthy individuals (83% male, mean age of 33.2±0.93 years) by using qPCR. Of the 20 patients, 8 had post-STEMI LVR according to echocardiographic evaluation, and the others did not. Clinical biochemical data including total cholesterol, HDL-C, LDL-C, LDH and NT-pro-BNP were collected from the patients with STEMI at same time as exosome miRNAs assessment. Specific exosome miRNAs for LVR were identified by using qPCR. Correlations between the dysregulated exosome miRNAs and the clinical biochemical parameters in patients with STEMI were analyzed using spearman correlation test.

Results

Five exosome miRNAs including hsa-miR-181a-3p (p&lt;0.05, fold change = 0.59), let-7d-3p (p=0.01, fold change = 0.51), hsa-miR-224-5p (p&lt;0.01, fold change = 0.11), hsa-miR-23a-3p (p&lt;0.01, fold change = 1.42) and miR-874-3p (p&lt;0.01, fold change = 0.48) were dysregulated in the post-STEMI patients comparing with the healthy individuals. Among them, the exosome miR-181a-3p (p=0.01, fold change = 0.09) and let-7d-3p (p=0.01, fold change = 0.16) were significantly lower expressed in patients with LVR compared to those without (Figure 1). There was no significant difference in expression of the other three miRNAs between patients with and without LVR. Exosome hsa-miR-874-3p positively associated with LDH (p&lt;0.01, r=0.50) in all the patients with STEMI. In vitro cell culture confirmed that the miR-874-3p mimics upregulated expression of apoptosis related gene BMF (p&lt;0.05, fold change = 1.7) in cardiomyocyte. Exosome hsa-miR-23a-3p and hsa-miR-224-5p positively correlated with both HDL-C (p&lt;0.01, r=0.61; p=0.02, r=0.50) and LDL-C (p=0.02, r=0.50; p&lt;0.05, r=0.52) in all patients with STEMI. No correlation between the dysregulated exosome miRNAs and cholesterol or NT-ProBNP was observed (Figure 2).

Conclusions

Circulating exosome miR-181a-3p and let-7d-3p might play a potential role in LVR in patients 3–6 months after STEMI. Exosome hsa-miR-874-3p might be associated with cardiomyocyte injury. Hsa-miR-23a-3p and hsa-miR-224-5p demonstrated an activity in regulation of lipid metabolism and biosynthesis in patients with STEMI.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): This work was supported by grants from the 3×3 Clinical Scientist Fund of Sun Yat-sen Memorial Hospital

Photocatalytic performance of heterojunction S-Tyr-NDI-Tyr/TiO2 formed by self-assembled naphthalimide derivatives and titanium dioxide

In this paper, a type of heterojunction photocatalyst S-Tyr-NDI-Tyr/TiO₂ was prepared by self-assembly of tyrosine-substituted naphthamide (NDA) and bonding with titanium dioxide. The self-assembly process and driving force of monomer M-Tyr-NDI-Tyr were simulated by theoretical calculation. Taking atenolol as the target pollutant, the photocatalytic performance of the heterojunction photocatalyst under visible light was studied, and the degradation products were analyzed by mass spectrometry. The environmental toxicity of photocatalytic process was evaluated by luminescent bacteria. The principle of high photocatalytic activity of S-Tyr-NDI-Tyr/TiO₂ heterojunction photocatalyst was proposed by analyzing the fluorescence spectrum, photocurrent density and resistance, electron paramagnetic resonance spectrum, free radical capture experiment and energy band position of S-Tyr-NDI-Tyr/TiO₂ heterojunction photocatalyst. In addition, the photocatalytic degradation of different pollutants by S-Tyr-NDI-Tyr/TiO₂ heterojunction photocatalyst was also studied. This work will provide a useful example for the further development of new and efficient organic supramolecular/inorganic semiconductor composite photocatalysts.

Defect density modulation of La2TiO5: An effective method to suppress electron-hole recombination and improve photocatalytic nitrogen fixation

Highly active and efficient photocatalysts are crucial for the exploration of ammonia synthesis because of the serious problem of energy deficiency. La₂TiO₅ (LTO) perovskite materials have great advantages in the field of photocatalytic nitrogen fixation because of the broadly diversified properties. The rational design of surface defect is a valid method to modulate photoinduced charge traps and create defect energy levels, especially it is an effective way to suppress the photoinduced charge recombination. Herein, LTO was obtained by a simple sol-gel method and was further reduced by NaBH₄ to introduce oxygen defect on its surface. UV-vis spectra proved that the surface defects could reduce the band gap value of samples, which is beneficial for improving photocatalytic nitrogen fixation activity. For the best photocatalytic samples with good cycle stability, the nitrogen fixation rate is 158.13 μmol·g^-1·h^-1. The mechanism of photocatalytic nitrogen fixation was proposed by the PL, XPS, and PEC results, which provided possibilities for exploring more promising perovskite catalysts in the field of nitrogen fixation.

Constructing Zn-P charge transfer bridge over ZnFe2O4-black phosphorus 3D microcavity structure: Efficient photocatalyst design in visible-near-infrared region

Black phosphorus (BP) is one of the most promising visible-near-infrared light-driven photocatalysts with favorite photoelectric properties and unique tunable direct band gap. Nevertheless, the further development of BP is hindered by the fast carrier recombination rate and high Gibbs free energy. Herein, an innovative strategy is developed for the controllable construction of Zn-P bonds induced zinc ferrite/black phosphorus (ZnFe₂O₄-BP) three dimensions (3D) microcavity structure. The Zn-P bonds serve as an efficient channel to optimize the carrier transport and Gibbs free energy of BP simultaneously. Besides, the unique 3D core-shell microcavity structure maintains the multiple reflections of sunlight inside the catalysts, which greatly improves the sunlight utilization upon photocatalysis. An optimized photocatalytic hydrogen production rate of 560 µmol h^-1g^-1 under near-infrared light (>820 nm) is achieved. A possible photocatalytic mechanism is proposed based on a series of experimental characterizations and theoretical calculations, this work provides a new sight to design high-quantity BP-based full-spectrum photocatalysts for solar energy conversion.

Pressure-Engineered Optical and Charge Transport Properties of Mn2+/Cu2+ Codoped CsPbCl3 Perovskite Nanocrystals via Structural Progression

In this work, compared with the corresponding pure CsPbCl₃ nanocrystals (NCs) and Mn²⁺-doped CsPbCl₃ NCs, Mn²⁺/Cu²⁺-codoped CsPbCl₃ NCs exhibited improved photoluminescence (PL) and photoluminescence quantum yields (PL QYs) (57.6%), prolonged PL lifetimes (1.78 ms), and enhanced thermal endurance (523 K) as a result of efficient Mn²⁺ doping (3.66%) induced by the addition of CuCl₂. Furthermore, we applied pressure on Mn²⁺/Cu²⁺-codoped CsPbCl₃ NCs to reveal that a red shift of photoluminescence followed by a blue shift was caused by band gap evolution and related to the structural phase transition from cubic to orthorhombic. Moreover, we also found that under the preheating condition of 523 K, such phase transition exhibited obvious morphological invariance, accompanied by significantly enhanced conductivity. The pressure applied to the products treated with high temperature enlarged the electrical difference and easily intensified the interface by closer packaging. Interestingly, defect-triggered mixed ionic and electronic conducting (MIEC) was observed in annealed NCs when the applied pressure was 2.9 GPa. The pressure-dependent ionic conduction was closely related to local nanocrystal amorphization and increased deviatoric stress, as clearly described by in situ impedance spectra. Finally, retrieved products exhibited better conductivity (improved by 5-6 times) and enhanced photoelectric response than those when pressure was not applied. Our findings not only reveal the pressure-tuned optical and electrical properties via structural progression but also open up the promising exploration of more amorphous all-inorganic CsPbX₃-based photoelectric applications.

Photocatalytic Performance and Mechanism Research of Ag/HSTiO2 on Degradation of Methyl Orange

The Sol-gel method is successfully used to prepare high specific surface area TiO₂ (HSTiO₂). Then, the photodeposition method is used to composite silver particles with HSTiO₂. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and UV-vis spectroscopy are used to characterize the Ag/HSTiO₂ nanocomposites. It can be concluded that the prepared TiO₂ has a large specific surface area, reaching 125.5 m² g^-1. Additionally, the addition of silver particles successfully broadens the photoresponse range from the UV region to the visible light region. In order to evaluate the photocatalytic activity of Ag/HSTiO₂, we conducted the methyl orange degradation test. The results showed that the photocatalytic activity of the sample is significantly higher than that of pure TiO₂.

Using artificial intelligence algorithms to identify existing knowledge within the back pain literature

PURPOSE

Artificial intelligence algorithms can now identify hidden data patterns within the scientific literature. In 2019, these algorithms identified a thermoelectric material within the pre-2009 chemistry literature; years before its discovery in 2012. This approach inspired us to apply this algorithm to the back pain literature as the cause of back pain remains unknown in 90% of cases.

METHODS

We created a subset of all PubMed abstracts containing "back" and "pain" and then trained the Word2vec algorithm to predict word proximity. We then identified word pairings having high vector proximities between three spinal domains: anatomy, pathology and treatment. We plotted both between-domain and within-domain proximities then used the highest proximity pairs as ground truths in analogy testing to identify known associations (e.g., Canal is to Stenosis as Multifidus is to ?) RESULTS: We found  50,038 abstracts resulting in 27,984 unique words and 108,252 instances of "back pain". Ground truth pairings ranged in proximity from 0.86 to 0.70. Plotting revealed unique proximity representations between the three spine domains. From analogy testing, we identified 13 known word associations (pars_interarticularis is to stress_reaction as nerve_root is to compression).

CONCLUSIONS

Artificial intelligence algorithms can successfully extract complex concepts from back pain literature. While use of AI algorithms to discover potentially unknown word associations requires future validation, our results provide investigators with a novel tool to generate new hypotheses regarding the origins of LBP and other spine related topics. To encourage use of these tools, we have created a free web-based app for investigator-driven queries.

Preparation and Photocatalytic Performance of Dumbbell Ag2CO3-ZnO Heterojunctions

Dumbbell Ag₂CO₃-ZnO heterojunctions were synthesized for the first time via a simple in situ precipitation method. The as-prepared Ag₂CO₃-ZnO heterojunction showed high photocatalytic activity in the decomposition of methyl orange aqueous solution under simulated solar irradiation. The high improvement of photocatalytic activity compared to that of pure ZnO can be attributed to the formation of the Ag₂CO₃-ZnO heterojunction. Furthermore, the mechanism of photocatalytic activity was investigated in detail. The free radical trapping experiments indicated that the superoxide radical (·O₂ ^-) was an important active species in the photocatalytic process. This paper provides a new prospect for the preparation of photocatalysts with high catalytic performance in the degradation of dye wastewater.

Photocatalytic Performance and Mechanistic Research of ZnO/g-C3N4 on Degradation of Methyl Orange

Highly dispersed ZnO/g-C₃N₄ composites with different doping ratios of g-C₃N₄ were prepared by a hydrothermal method. The preparation method is simple and the energy consumption is low. The composite samples were used to degradate the methyl orange solution. They all showed excellent photocatalytic activity and cycling stability. The optimal loading content of g-C₃N₄ was investigated, and the mechanism of enhanced photocatalytic activity was studied in detail. This study provides a promising photocatalytic material for the removal of organic pollutants.

Chitinase-like protein YKL-40 regulates human bronchial epithelial cells proliferation, apoptosis, and migration through TGF-β1/Smads pathway

In order to study the effects of chitinase-like protein YKL-40 on proliferation, apoptosis, and migration of human bronchial epithelial cell line (BEAS-2B), and the underlying mechanisms, we cultured BEAS-2B alone or with different concentrations of YKL-40. thiazolyl blue tetrazolium bromide (MTT) assay was used to examine the cell proliferation. Annexin V-fluorescein isothiocyanate isomer (FITC)/propidium iodide staining and scratch assay were performed to test the cell apoptosis and migration. The concentrations of transforming growth factor-β1 (TGF-β1), Smad3, Smad7, alpha-smooth muscle actin (α-SMA), interleukin-4 (IL-4), IL-6, and IL-8 in the cell culture supernatant were detected by enzyme-linked immunosorbent assay. The messenger RNA and protein levels of YKL-40, TGF-β1, Smad3, Smad7, and α-SMA were detected by reverse transcription polymerase chain reaction and Western blot. BEAS-2B cells cultured with different concentrations of YKL-40 showed significantly higher cell proliferation and migration and inflammatory cytokines compared with that of control group, while the cell apoptosis was significantly lower than that of control group (p < 0.05). In addition, BEAS-2B cells cultured with YKL-40 had increased TGF-β1, Smad3, Smad7, and α-SMA levels in the supernatant, compared with that of BEAS-2B cells cultured alone (p < 0.05). Furthermore, LY364947, as TGF-β1/Smads signaling pathway inhibitor, decreased cell proliferation and migration ability and enhanced cell apoptosis of BEAS-2B cells compared with control group (p < 0.05). However, YKL-40 administration reversed the effect of LY364947 on the biological behavior of BEAS-2B cells. YKL-40 could affect the biological behaviors of BEAS-2B cells, which might be related to the TGF-β1/Smads pathway.

Tunable photoluminescence and an enhanced photoelectric response of Mn2+-doped CsPbCl3 perovskite nanocrystals via pressure-induced structure evolution

Mn²⁺:CsPbCl₃ nanocrystals (NCs) were synthesized using a modified one-pot injection method, which exhibits significantly improved thermal stability. For the first time, the pressure-treated optical and structural properties of synthetic Mn²⁺:CsPbCl₃ NCs were further investigated, and their associated intriguing electrical and photoelectric properties were revealed from impedance spectra and photocurrent measurements under compression. The pressure-dependent photoluminescence experienced an initial redshift before 1.7 GPa followed by a continuous blueshift, as evidenced by the bandgap shifts. High-pressure XRD spectra uncovered a cubic-to-orthorhombic structural transition at about 1.1 GPa and subsequent amorphization upon further compression, which was fully reversible. Furthermore, the sample annealing from 340 K drove grain growth and decreased grain boundary resistance at ambient pressure. The compression further decreased the grain boundary barrier and improved the electrical conductivity (up to ∼10^-2Ω^-1 cm^-1) of the thermally annealed Mn²⁺:CsPbCl₃ NC surface. Simultaneous photocurrent enhancement of thermally annealed NCs was also achieved as expected, and reached optimal performance at 0.7 GPa. Strikingly, after the pressure cycling (loading-releasing), the results show that thermally annealed Mn²⁺:CsPbCl₃ NCs gained preservable higher electrical conductivity (∼10 times increase) and an improved photoelectric response compared to the ambient state before compression. This work proves that high pressure is useful for opening the versatility in the structure and properties of metal-halide perovskite nanocrystals leading to a promising way for superior optoelectronic materials-by-design.

Therapeutic effect of ginsenoside Rg1 on mastitis experimentally induced by lipopolysaccharide in lactating goats

Escherichia coli is a cause of subclinical and clinical mastitis in dairy cattle and goats, and sometimes causes severe clinical disease that may result in death of the animal. Previous investigation showed that ginsenoside Rg1 extracted from Panax ginseng C.A. Meyer (Araliaceae) has an anti-inflammatory effect on the sepsis induced by E. coli lipopolysaccharide via competitive binding to toll-like receptor 4. We hypothesized that intravenous injection of Rg1 had therapeutic effect on mastitis experimentally induced by intramammary infusion of lipopolysaccharide in lactating goats. In this study, 9 lactating goats were randomly assigned to 1 of the 3 groups: (1) lipopolysaccharide intramammary infusion + saline intravenous injection, (2) lipopolysaccharide intramammary infusion + Rg1 intravenous injection, and (3) saline intramammary administration + saline intravenous injection. Because no adverse clinical signs were observed after intramammary infusion of saline and intravenous injection of Rg1 in a preliminary experiment, and available qualified goats were limited in this study, this treatment was not included in this study. One udder half of each goat received intramammary infusion of lipopolysaccharide (50 μg/kg of body weight; groups 1 and 2) or saline solution (group 3), and the other half was infused with 2 mL of saline solution at h 0. Afterward, intravenous injections of saline solution (groups 1 and 3) or Rg1 (2.5 mg/kg of body weight; group 2) were administered at h 2 and 4 post-lipopolysaccharide challenge. Blood and milk samples were collected 3, 6, 9, 12, 15, 18, 21, 24, 48, and 72 h post-lipopolysaccharide challenge, and clinical signs were monitored hourly after lipopolysaccharide challenge within the first 10 h and at the same time points as blood samples. The results showed that Rg1 treatment downregulated rectal temperature, udder skin temperature, udder girth, milk somatic cell count, and N-acetyl-β-d-glucosaminidase and upregulated milk production, lactose, and recovered blood components, such as white blood cells, neutrophils, lymphocytes, total proteins, albumin, and globulin. Considering the positive therapeutic effect on lipopolysaccharide-induced mastitis in goats presented in this study as well as the anti-inflammatory activity found previously, the botanical Rg1 deserves further study as a therapeutic agent in the treatment of E. coli mastitis in dairy animals.

Correlation between Structural Changes and Electrical Transport Properties of Spinel ZnFe2O4 Nanoparticles under High Pressure

The structural phase transition of synthetic ZnFe₂O₄ nanoparticles (ZFO NPs) is investigated as a function of pressure up to 40.6 GPa at room temperature for the first time, and its associated intriguing electrical transport properties are resolved from in situ impedance spectra and magnetoresistivity measurements. Significant anomalies are observed in the properties of the grain boundary resistance ( R_gb), the relaxation frequency ( f_max), and the relative permittivity (ε_r) in the ZFO NPs under the pressures around 17.5-21.5 GPa. These anomalies are believed to be correlated with a cubic-to-orthorhombic phase transition of ZnFe₂O₄ at the pressures between 21.9 and 25.7 GPa, which is found to be partially reversible. The pressure-tuned dielectric properties are measured for the cubic and the orthorhombic phases of ZFO, respectively. Remarkably, R_gb decreases up to 6 orders of magnitude as a function of pressure in the cubic phase. The dielectric polarization is obviously strengthened with increased f_max and decreased ε_r with pressure in the orthorhombic phase. Furthermore, it is confirmed that the external pressure effectively improves the electrochemical stability of the sample based on the cycled measurements of the impedance spectra at various pressures. The changes in the complex permittivity (ε', ε″) and the dielectric loss tangent (tan δ) with frequency reveal the irreversible increase in the dielectric loss accompanied by phase transition. The MR measurements indicate that ZFO NPs are superparamagnetic under high pressure of up to 40 GPa. The transmission electron microscopy images reflect the decrease in the grain boundary number and some local amorphization of grains after compression, which provides good explanations for the changes in the electrical transport properties as a function of pressure. Herein, the structural and electrical properties of ZnFe₂O₄ NPs generated are preserved by quenching the high-pressure phase to ambient conditions, thus providing great choices of ferrites materials for a variety of applications.

A Knowledge Base Completion Model Based on Path Feature Learning

Large-scale knowledge bases, as the foundations for promoting the development of artificial intelligence, have attracted increasing attention in recent years. These knowledge bases contain billions of facts in triple format; yet, they suffer from sparse relations between entities. Researchers proposed the path ranking algorithm (PRA) to solve this fatal problem. To improve the scalability of knowledge inference, PRA exploits random walks to find Horn clauses with chain structures to predict new relations given existing facts. This method can be regarded as a statistical classification issue for statistical relational learning (SRL). However, large-scale knowledge base completion demands superior accuracy and scalability. In this paper, we propose the path feature learning model (PFLM) to achieve this urgent task. More precisely, we define a two-stage model: the first stage aims to learn path features from the existing knowledge base and extra parsed corpus; the second stage uses these path features to predict new relations. The experimental results demonstrate that the PFLM can learn meaningful features and can achieve significant and consistent improvements compared with previous work.

[Modulation of umbilical cord blood mesenchymal stem cells on Treg cells in the patients with aplastic anemia]

Objective: To research the modulation of Umbilical cord blood mesenchymal stem cells on the number and function of Treg cells in the patients with aplastic anemia, as well as the expression of LFA-1 on Treg cells. Methods: A total of 20 newly diagnosed NSAA patients were collected from May 2015 to Jun 2016 in Department of Hematopathy, General Hospital of Jinan Military, and 10 healthy volunteers were recruited as controls. Separation of the patients and controls with peripheral blood mononuclear cells were divided into two groups, including PBMCs culture alone, PBMCs co-culture with UC-MSCs, application of flow cytometry detect respectively the proportion of the Treg cells and the expression of LFA-1 on Treg cells under different culture conditions. The Treg cells and CD4(+) CD25(-)T lymphocyte were separated by magnetic cell sorting (MACS) system, CFSE label CD4(+) CD25(-)T lymphocyte, comparing the inhibitive function of Treg cells on CD4(+) CD25(-)T lymphocyte with or without co-culture with UC-MSCs. Results: The intensity of fluorescence expression of LFA-1 on T lymphocyte in aplastic anemia increased obviously((71.4±10.1)vs(52.5±8.7) , P=0.002), but the LFA-1 expressed on Treg cells had no significant difference(P=0.199). After co-cultured with UC-MSCs, the proportion of LFA-1 on Treg cells in aplastic anemia reduced greatly ((20.96±1.76)% vs(44.26±1.19)%, P=0.012), at the same time, UC-MSCs increased the proportion of Treg cells obviously ((5.33±1.14)%vs(1.94±0.65)%, P=0.003), but the effect of Treg cells on the mean frquency of dividing CD4(+) CD25(-)T lymphocyte had no significant difference with or without co-culture with UC-MSCs(P=0.290). Conclusions: The intensity of fluorescence expression of LFA-1 on lymphocyte in aplastic anemia increases obviously, indicating the possible pathogenesis of AA. UC-MSCs inhibit the expression of LFA-1 on Treg cells and enhance the proportion of Treg cells, but UC-MSCs doesn't directly improve the immunosuppression of single Treg cells.

The association of DLG5 polymorphisms with inflammatory bowel disease: a meta-analysis of 25 studies

OBJECTIVE

The aim of this study was to explore the association of polymorphisms in DLG5 gene (G113A, C4136A and e26) with inflammatory bowel disease (IBD) risk.

MATERIALS AND METHODS

A total of 25 studies involved 26583 subjects were pooled for analysis. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to pool the effect size.

RESULTS

For G113A variant, a significant association was observed with CD risk in children (A vs. G: OR = 0.745, 95% CI = 0.569-0.977) and high quality studies (A vs. G: OR = 0.913, 95% CI = 0.850-0.981). Additionally, the results of genotype-phenotype analysis suggested G113A variant was associated with colonic involvement in CD. However, in overall population, the results indicated G113A variant was not associated with CD or UC. We also provided evidence that C4136A polymorphism had different effects on CD risk between Europeans (AA vs. CC: OR = 3.239, 95% CI = 1.149-9.136) and Asians (AA vs. CC: OR = 0.511, 95% CI = 0.299-0.873). For UC, patients with AA genotype of C4136A variant had a significantly increased UC risk (AA vs. CC: OR = 3.877, 95% CI = 1.168-12.867). Finally, no association was detected with G113A or e26 polymorphism in CD or UC patients.

CONCLUSIONS

This meta-analysis indicated G113A variant may be significantly associated with CD risk in children and colonic involvement.

Misfolding Ectodomain Mutations of the Lutropin Receptor Increase Efficacy of Hormone Stimulation

We demonstrate 2 novel mutations of the LHCGR, each homozygous, in a 46,XY patient with severe Leydig cell hypoplasia. One is a mutation in the signal peptide (p.Gln18_Leu19ins9; referred to here as SP) that results in an alteration of the coding sequence of the N terminus of the mature mutant receptor. The other mutation (p.G71R) is also within the ectodomain. Similar to many other inactivating mutations, the cell surface expression of recombinant human LHR(SP,G71R) is greatly reduced due to intracellular retention. However, we made the unusual discovery that the intrinsic efficacy for agonist-stimulated cAMP in the reduced numbers of receptors on the cell surface was greatly increased relative to the same low number of cell surface wild-type receptor. Remarkably, this appears to be a general attribute of misfolding mutations in the ectodomains, but not serpentine domains, of the gonadotropin receptors. These findings suggest that there must be a common, shared mechanism by which disparate mutations in the ectodomain that cause misfolding and therefore reduced cell surface expression concomitantly confer increased agonist efficacy to those receptor mutants on the cell surface. Our data further suggest that, due to their increased agonist efficacy, extremely small changes in cell surface expression of misfolded ectodomain mutants cause larger than expected alterations in the cellular response to agonist. Therefore, for inactivating LHCGR mutations causing ectodomain misfolding, the numbers of cell surface mutant receptors on fetal Leydig cells of 46,XY individuals exert a more exquisite effect on the relative severity of the clinical phenotypes than already appreciated.

Glycogen synthase kinase-3 reduces acetylcholine level in striatum via disturbing cellular distribution of choline acetyltransferase in cholinergic interneurons in rats

Cholinergic interneurons, which provide the main source of acetylcholine (ACh) in the striatum, control the striatal local circuits and deeply involve in the pathogenesis of neurodegenerative diseases. Glycogen synthase kinase-3 (GSK-3) is a crucial kinase with diverse fundamental functions and accepted that deregulation of GSK-3 activity also plays important roles in diverse neurodegenerative diseases. However, up to now, there is no direct proof indicating whether GSK-3 activation is responsible for cholinergic dysfunction. In the present study, with combined intracerebroventricular injection of Wortmannin and GF-109203X, we activated GSK-3 and demonstrated the increased phosphorylation level of microtubule-associated protein tau and neurofilaments (NFs) in the rat striatum. The activated GSK-3 consequently decreased ACh level in the striatum as a result of the reduction of choline acetyltransferase (ChAT) activity. The alteration of ChAT activity was due to impaired ChAT distribution rather than its expression. Furthermore, we proved that cellular ChAT distribution was dependent on low phosphorylation level of NFs. Nevertheless, the cholinergic dysfunction in the striatum failed to induce significant neuronal number reduction. In summary, our data demonstrates the link between GSK-3 activation and cholinergic dysfunction in the striatum and provided beneficial evidence for the pathogenesis study of relevant neurodegenerative diseases.

Ministry of Health clinical practice guidelines: Chronic Hepatitis B Infection

The Ministry of Health (MOH) publishes clinical practice guidelines on Chronic Hepatitis B Infection to provide doctors and patients in Singapore with evidence-based guidance on managing important medical conditions. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Chronic Hepatitis B Infection, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website (http://www.moh.gov.sg/mohcorp/publications.aspx?id=26108). The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Comparison of intra-coronary cell transplantation after myocardial infarction: Autologous skeletal myoblasts versus bone marrow mesenchymal stem cells

Cell transplantation promises restoration of cardiac function after myocardial infarction (MI). Comparison of intracoronary cell transplantation with skeletal myoblasts (SMs) versus bone marrow mesenchymal stem cells (BM-MSCs) was carried out in rabbits with MI induced by ligation of the left anterior descending artery. The infarction-affected artery was injected with SMs, BM-MSCs or cell-free medium (control) 24 h post-infarction (n = 15 per group). At baseline, there were no differences in cardiac parameters between the groups. At 4 weeks post-transplantation, left ventricular ejection fraction significantly improved and left ventricular end-diastolic diameter was significantly decreased in the cell-treated groups compared with pre-transplantation and the control group. Engrafted cells were found in all of the cell-treated rabbits. The cell-treated animals had significantly higher numbers of neovessels compared with the control. No significant difference was seen between the SM and BM-MSC groups. In conclusion, intra-coronary transplantation of SMs and BM-MSCs induced neoangiogenesis with comparable enhancements of cardiac performance and reduced cardiac remodelling in a rabbit MI model.

Influence of hydroxyethyl starch 130/0.4 in pulmonary neutrophil recruitment and acute lung injury during polymicrobial sepsis in rats

BACKGROUND

Acute lung injury (ALI) is a progressive syndrome associated with significant mortality in sepsis patients. Neutrophils are key cells in the inflammatory response that characterizes ALI. This study was designed to explore the effects of hydroxyethyl starch (HES) 130/0.4 (a novel plasma substitute) on pulmonary neutrophil recruitment and associated ALI in a rat sepsis model induced by cecal ligation and puncture (CLP).

METHODS

Animals were randomly assigned to six groups [saline control; CLP and saline; CLP and HES (7.5, 15 and 30 ml/kg); and HES control], subjected to CLP and infused with or without HES 130/0.4 4 h after CLP. Six hours later, the pulmonary capillary permeability (PCP), myeloperoxidase (MPO) activity, lung histological changes, tumor necrosis factor-alpha, interleukin-1beta and cytokine-induced neutrophil chemoattractant levels, P-selectin mRNA expression and nuclear factor-kappa B (NF-kappaB) activation were measured.

RESULTS

Resuscitation with HES 130/0.4 significantly attenuated the CLP-induced increase in PCP, MPO activity, cytokine/chemokine levels, mRNA expression of P-selectin and NF-kappaB activation, all of which are involved in the recruitment of neutrophils. Groups receiving the higher doses of HES 130/0.4 (15 and 30 ml/kg) were more adequately resuscitated.

CONCLUSION

HES 130/0.4 can inhibit CLP-induced neutrophil recruitment and subsequent ALI by attenuating cytokines/chemokines, adhesion molecule-mediated inflammation and NF-kappaB activation.

Effects of Anti-Bursin Monoclonal Antibody on Immunosuppression in the Duck (Cherry Valley Duck)

To study the immunologic function of bursin, we analyzed the effects of anti-bursin monoclonal antibody (mAb) on the immunosuppression in ducks (Cherry Valley duck) by injecting various doses of the anti-bursin mAb into 13-d duck embryos. After hatch, cell-mediated immune activity and humoral responses were studied using lymphocyte proliferation test, tube agglutination test, and indirect enzyme-linked immunosorbent assay to detect anti-Escherichia coli antibodies and antibodies to Riemerella anatipestifer, respectively. Simultaneously, relative weights (BW-adjusted) of bursa of Fabricius (BF), spleen, and thymus were determined. Additionally, the morphology of BF, spleen, and thymus was examined at various ages using conventional histology. Follicle morphology of BF was analyzed by image analysis. The results indicated that anti-bursin mAb markedly decreased duck lymphocyte proliferation, the antibody-producing ability to bacteria, as well as the relative BF weight. Moreover, the anti-bursin mAb hindered the development of BF follicles.

Trace eyeblink conditioning is hippocampally dependent in mice

The goal of this study was to determine whether trace eyeblink conditioning is a hippocampally dependent associative learning task in the mouse. First, we examined trace intervals of 0, 250, and 500 ms to determine a relatively long trace interval that would support eyeblink conditioning in young adult C57BL/6 mice. Mice rapidly acquired conditioned responses (CRs) with a 0-ms trace interval, acquired CRs with a 250-ms trace interval in approximately 2 days (2 sessions per day), and showed little acquisition with a 500-ms trace interval. Control mice were presented randomly unpaired stimuli and failed to show conditioning. We then determined the effect of lesioning dorsal hippocampal neurons on trace eyeblink conditioning. The hippocampus was injected bilaterally with vehicle (phosphate-buffered saline), 0.1% ibotenic acid, or 1% ibotenic acid. The vehicle group showed >60% CRs. The 0.1% group showed significantly fewer CRs (35-45%). The 1% group showed a level of CRs similar to that of the control mice. All the lesioned mice exhibited >60% CRs when subsequently trained with a 0-ms trace interval. A regression analysis indicated that the volume of area CA1 lesioned was more predictive of the behavioral impairment than the lesion volume of either CA3 or dentate gyrus, or even the total lesion volume. We conclude that dorsal hippocampal neurons play a critical role in eyeblink conditioning when a 250-ms trace interval is used with the C57BL/6 mouse, and that this paradigm will be useful for studying behavior and the in vivo and in vitro electrophysiology of hippocampal neurons in normal and transgenic or knockout mice.

Fatal hepatitis B reactivation following discontinuation of nucleoside analogues for chronic hepatitis B

BACKGROUND

Nucleoside analogues such as lamivudine for chronic hepatitis B have an excellent safety profile while patients are on therapy but reactivation flares occur in 19-50% of patients after stopping therapy, some of whom develop liver decompensation.

AIMS

To describe and report three cases who developed fatal hepatitis B reactivation after stopping nucleoside analogue therapy.

SUBJECTS AND RESULTS

Three patients are described who developed hepatitis B reactivation and liver decompensation after stopping therapy. One of the three patients was participating in a famciclovir trial and the other two were receiving lamivudine therapy for active hepatitis B infection. All three patients had documented hepatitis B flares, and all had hepatitis B virus DNA detected at that time. All patients developed decompensated liver disease despite one patient having had a prior liver biopsy showing absence of cirrhosis. Reintroduction of lamivudine therapy failed to halt progression of liver decompensation even after hepatitis B virus DNA had been demonstrated to be absent. Sequencing for lamivudine resistant mutants in two cases where serum was available failed to show evidence of mutations associated with lamivudine resistance.

CONCLUSION

Hepatitis B virus reactivation, leading to decompensation and death, are possible complications of treatment withdrawal and patients should be monitored closely if therapy is ceased.

A depressant insect toxin with a novel analgesic effect from scorpion Buthus martensii Karsch

A new peptide named BmK dITAP3 from scorpion Buthus martensii Karsch (BmK) has been identified to possess a dual bioactivity, a depressant neurotoxicity on insects and an analgesic effect on mice. The bioassays also showed that the peptide was definitely devoid of the neurotoxicity on mammals, which indicated that the analgesic effect of BmK dITAP3 could not be ascribed to the syndromic effects of a mammalian neurotoxicity. BmK dITAP3 exhibited 43.0% inhibition efficiency of the analgesic effect on mice at a dose of 5 mg/kg and the FPU value of 0.5 microg/body (approximately 30 mg) on the fly larvae. The pI value and the molecular mass determined by MALDI-TOF MS for dITAP3 were 6.5 and 6722.7, respectively. Its first 15 N-terminal residues were determined by Edman degradation, based on which the full amino acid sequence was deduced from the cDNA sequence encoding the peptide with 3'-RACE. Circular dichroism and sequence based prediction analyses showed dITAP3 may have a similar molecular scaffold as the most scorpion toxins but with features of the more beta structures and much less of alpha helix. The details of the purification, characterization and sequencing as well as the sequence comparison with other depressant insect toxins and the correlation between the analgesic effect and the insect toxicity will be reported and discussed, respectively.

Growth hormone (GH)-induced dimerization inhibits phorbol ester-stimulated GH receptor proteolysis

Growth hormone (GH) initiates its cellular action by properly dimerizing GH receptor (GHR). A substantial fraction of circulating GH is complexed with a high-affinity GH-binding protein (GHBP) that in many species can be generated by GHR proteolysis and shedding of the receptor's ligand-binding extracellular domain. We previously showed that this proteolysis 1) can be acutely promoted by the phorbol ester phorbol 12-myristate 13-acetate (PMA), 2) requires a metalloprotease activity, 3) generates both shed GHBP and a membrane-associated GHR transmembrane/cytoplasmic domain remnant, and 4) results in down-regulation of GHR abundance and GH signaling. Using cell culture model systems, we now explore the effects of GH treatment on inducible GHR proteolysis and GHBP shedding. In human IM-9 lymphocytes, which endogenously express GHRs, and in Chinese hamster ovary cells heterologously expressing wild-type or cytoplasmic domain internal deletion mutant rabbit GHRs, brief exposure to GH inhibited PMA-induced GHR proteolysis (receptor loss and remnant accumulation) by 60-93%. PMA-induced shedding of GHBP from Chinese hamster ovary transfectants was also inhibited by 70% in the presence of GH. The capacity of GH to inhibit inducible GHR cleavage did not rely on JAK2-dependent GH signaling, as evidenced by its continued protection in JAK2-deficient gamma2A rabbit GHR cells. The GH concentration dependence for inhibition of PMA-induced GHR proteolysis paralleled that for its promotion of receptor dimerization (as monitored by formation of GHR disulfide linkage). Unlike GH, the GH antagonist, G120K, which binds to but fails to properly dimerize GHRs, alone did not protect against PMA-induced GHR proteolysis; G120K did, however, antagonize the protective effect of GH. Our data suggest that GH inhibits PMA-induced GHR proteolysis and GHBP shedding by inducing GHR dimerization and that this effect does not appear to be related to GH site 1 binding, GHR internalization, or GHR signaling. The implications of these findings with regard to GH signaling and GHR down-regulation are discussed.

Extended lamivudine treatment in patients with chronic hepatitis B enhances hepatitis B e antigen seroconversion rates: results after 3 years of therapy

A study in Chinese patients with chronic hepatitis B showed that treatment with lamivudine for 1 year significantly improves liver histology and enhances hepatitis B e antigen (HBeAg) seroconversion compared with placebo. Fifty-eight patients from this 1-year study have received long-term treatment with lamivudine 100 mg; the outcome of 3 years of lamivudine is reported here. Before treatment, all patients had detectable HBeAg. HBeAg seroconversion (HBeAg-negative, anti-HBe-positive), hepatitis B virus (HBV)-DNA suppression, alanine transaminase (ALT) normalization, emergence of YMDD variant HBV, liver histology, and long-term safety were assessed. After 3 years of continuous treatment with lamivudine 100 mg daily, 40% (23 of 58) of patients achieved HBeAg seroconversion. In patients with baseline serum ALT >2 x upper limit of normal (ULN), the rate of HBeAg seroconversion was 65% (17 of 26). Median serum HBV-DNA concentrations were below the level of detection, and median ALT concentrations were within the normal range throughout 3 years of treatment. YMDD variant HBV emerged in 33 of 58 (57%) patients during the 3 years, of whom 9 (27%) achieved HBeAg seroconversion (6 after emergence of YMDD variant HBV). ALT levels and histologic scores after emergence of YMDD variant HBV did not show major deterioration. Lamivudine was well tolerated during 3 years of therapy. In conclusion, these data in Chinese patients with chronic hepatitis B show enhanced seroconversion rates with extended lamivudine treatment. Up to two thirds of patients with moderately elevated pretreatment ALT achieved HBeAg seroconversion after 3 years of therapy.

Phorbol ester- and growth factor-induced growth hormone (GH) receptor proteolysis and GH-binding protein shedding: relationship to GH receptor down-regulation

GH signals by interacting with GH receptor (GHR). A substantial fraction of circulating GH complexes with GH-binding protein (GHBP), which corresponds to the GHR extracellular domain. GHBP is generated by 1) alternative splicing of a common GHR precursor messenger RNA to encode secreted GHBP (the source of the vast majority of GHBP in rodents); and 2) proteolysis of the cell-associated GHR with shedding of GHBP (a mechanism operative in rabbits and humans). We previously observed that phorbol ester (PMA)-induced activation of protein kinase C (PKC) causes metalloprotease-mediated GHR proteolysis and GHBP shedding in human IM-9 lymphocytes. We now demonstrate that PMA-induced hydroxamate (IC3)-inhibitable GHR proteolysis and GHBP shedding were also detected in murine 3T3-F442A and 3T3-L1 preadipocytes and in Chinese hamster ovary (CHO) cells stably expressing rabbit GHR (rbGHR), although the degree of GHBP shedding was much smaller for murine GHR than for rabbit or human GHRs. PMA-induced GHR proteolysis in 3T3-F442A, 3T3-L1, and CHO-rbGHR cells was significantly reduced by pretreatment with mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 inhibitors, suggesting involvement of the mitogen-activated protein kinase pathway in regulating this PKC-dependent effect. In contrast, GHR proteolysis promoted by N-ethylmaleimide, although inhibited by IC3, was unaffected by inhibition of either PKC or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1. Thus, different pathways leading to metalloprotease-mediated receptor proteolysis are accessed by PMA vs. N-ethylmaleimide. To determine whether other, possibly more physiologically relevant, stimuli induce GHR proteolysis, we tested effects of platelet-derived growth factor (PDGF) and serum. Treatment of serum-deprived cells with PDGF (in 3T3-F442A cells) or serum (in 3T3-F442A and CHO-rbGHR cells) promoted GHR proteolysis, which was inhibited by IC3. Interestingly, PMA-, PDGF-, and serum-induced GHR proteolysis was associated with substantial decreases in GH-induced activation of Janus kinase-2, which were also prevented by IC3. These findings suggest that inducible metalloprotease-mediated GHR proteolysis constitutes an important mechanism of receptor down-regulation and modulation of GH signaling.

Chronic hepatitis B virus infection in Asian countries

Of the estimated 50 million new cases of hepatitis B virus (HBV) infection diagnosed annually, 5-10% of adults and up to 90% of infants will become chronically infected, 75% of these in Asia where hepatitis B is the leading cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). In Indonesia, 4.6% of the population was positive for HBsAg in 1994 and of these, 21% were positive for HBeAg and 73% for anti-HBe; 44% and 45% of Indonesian patients with cirrhosis and HCC, respectively, were HBsAg positive. In the Philippines, there appear to be two types of age-specific HBsAg prevalence, suggesting different modes of transmission. In Thailand, 8-10% of males and 6-8% of females are HBsAg positive, with HBsAg also found in 30% of patients with cirrhosis and 50-75% of those with HCC. In Taiwan, 75-80% of patients with chronic liver disease are HBsAg positive, and HBsAg is found in 34% and 72% of patients with cirrhosis and HCC, respectively. In China, 73% of patients with chronic hepatitis and 78% and 71% of those with cirrhosis and HCC, respectively, are HBsAg positive. In Singapore, the prevalence of HBsAg has dropped since the introduction of HBV vaccination and the HBsAg seroprevalence of unvaccinated individuals over 5 years of age is 4.5%. In Malaysia, 5.24% of healthy volunteers, with a mean age of 34 years, were positive for HBsAg in 1997. In the highly endemic countries in Asia, the majority of infections are contracted postnatally or perinatally. Three phases of chronic HBV infection are recognized: phase 1 patients are HBeAg positive with high levels of virus in the serum and minimal hepatic inflammation; phase 2 patients have intermittent or continuous hepatitis of varying degrees of severity; phase 3 is the inactive phase during which viral concentrations are low and there is minimal inflammatory activity in the liver. In general, patients who clear HBeAg have a better prognosis than patients who remain HBeAg-positive for prolonged periods of time. The outcome after anti-HBe seroconversion depends on the degree of pre-existing liver damage and any subsequent HBV reactivation. Without pre-existing cirrhosis, there may be only slight fibrosis or mild chronic hepatitis, but with pre-existing cirrhosis, further complications may ensue. HBsAg-negative chronic hepatitis B is a phase of chronic HBV infection during which a mutation arises resulting in the inability of the virus to produce HBeAg. Such patients tend to have more severe liver disease and run a more rapidly progressive course. The annual probability of developing cirrhosis varies from 0.1 to 1.0% depending on the duration of HBV replication, the severity of disease and the presence of concomitant infections or drugs. The annual incidence of hepatic decompensation in HBV-related cirrhosis varies from 2 to 10% and in these patients the 5-year survival rate drops dramatically to 14-35%. The annual risk of developing HCC in patients with cirrhosis varies between 1 and 6%; the overall reported annual detection rate of HCC in surveillance studies, which included individuals with chronic hepatitis B and cirrhosis, is 0.8-4.1%. Chronic hepatitis B is not a static disease and the natural history of the disease is affected by both viral and host factors. The prognosis is poor with decompensated cirrhosis and effective treatment options are limited. Prevention of HBV infection thorough vaccination is still, therefore, the best strategy for decreasing the incidence of hepatitis B-associated cirrhosis and HCC.

A distinct mutational spectrum of p53 and K-ras genes in lung cancer of workers with silicosis

Crystalline silica was recently classified as a human carcinogen by the International Agency for Research on Cancer (IARC). However, the direct genotoxic effect of silica in humans remains unclear. We examined the p53 and K-ras gene mutations in lung cancer in workers with silicosis (LCWS). DNA was extracted from paraffin-embedded tissues and examined by PCR-RFLP, PCR-SSCP, and DNA sequencing. The mutation frequencies of p53 gene were high, but the mutation distributions in exons and among the histological types of LCWS differed from those of common (i.e., not silicosis-related) lung cancer. Furthermore, no mutations in codon 12 of K-ras gene (predominant in common lung cancer) were found in LCWS. These findings in the mutational spectrum support a carcinogenic effect of silica dust at the DNA molecular level.

Effects of extended lamivudine therapy in Asian patients with chronic hepatitis B. Asia Hepatitis Lamivudine Study Group

BACKGROUND & AIMS

One-year lamivudine therapy significantly suppressed hepatitis B virus (HBV) replication, improved hepatic necroinflammatory activity, and prevented progression of fibrosis. However, the effects of prolonged therapy are unknown.

METHODS

A total of 334 Asian patients with chronic hepatitis B from a previously reported 1-year study were randomized to receive either lamivudine (100 or 25 mg) or placebo for another year. The effects of treatment on serum HBV-DNA suppression, alanine transaminase (ALT) normalization, and hepatitis B e antigen (HBeAg) seroconversion were measured. The presence of YMDD variant HBV and its effect were also determined.

RESULTS

A significantly greater proportion of patients achieved sustained HBV-DNA suppression and ALT normalization with 100 mg lamivudine daily for 2 years compared with lamivudine for 1 year followed by placebo for the second year (P<0.001). Daily lamivudine therapy for 2 years was safe and resulted in incremental HBeAg seroconversion from 17% at week 52 to 27% at week 104. HBeAg seroconversion during continued lamivudine therapy increased linearly with increasing pretherapy ALT levels (P< 0.001). Despite the emergence of YMDD mutant in 38% of the patients, they continued to clear serum HBeAg and maintain lower median serum HBV-DNA and ALT levels than baseline values. In contrast, ALT levels increased 8-12 weeks after switching from lamivudine to placebo, but returned to normal once lamivudine treatment was resumed.

CONCLUSIONS

Treatment with lamivudine for 2 years is both well tolerated and efficacious in patients with chronic hepatitis B.

Interferon monotherapy in chronic hepatitis B

Interferon-alpha (IFN-alpha) has been the only approved agent for the treatment of chronic hepatitis B in most countries, but this is rapidly changing. It is expensive, associated with frequent and unpleasant side effects, has limited efficacy and is ineffective in subjects with no/mild liver necro-inflammation. Loss of HBsAg and viral replication markers occur 6% and 20%, more often in IFN-treated subjects than controls. The most important factors that will predict favourable response to IFN-alpha therapy are elevated ALT and low serum HBV DNA levels. Chinese patients and children with active liver have similar response rates as Caucasian adults with equivalent ALT levels. Patients with HBeAg negative disease fare less well. Long-term follow up has shown that most IFN responders maintained their response although very few people have complete eradication of HBV.

The hinge of the human papillomavirus type 11 E2 protein contains major determinants for nuclear localization and nuclear matrix association

The E2 protein of papillomaviruses is a site-specific DNA binding nuclear protein. It functions as the primary replication origin recognition protein and assists in the assembly of the preinitiation complex. It also helps regulate transcription from the native viral promoter. The E2 protein consists of an amino-terminal (N) trans-acting domain, a central hinge (H) domain, and a carboxyl-terminal (C) protein dimerization and DNA binding domain. The hinge is highly divergent among papillomaviruses, and little is known about its functions. We fused the enhanced green fluorescent protein (GFP) with the full-length human papillomavirus type 11 (HPV-11) E2 protein and showed that the resultant fusion, called gfpE2, maintained transcription and replication functions of the wild-type protein and formed similar subnuclear foci. Using a series of GFP fusion proteins, we showed that the hinge conferred strong nuclear localization, whereas the N or C domain was present in both cytoplasm and nucleus. Biochemical fractionation demonstrated that the N domain and hinge, but not the C domain, independently associated with the nuclear matrix. Mutational analyses showed that a cluster of basic amino acid residues, which is conserved among many mucosotropic papillomaviruses, was required for efficient nuclear localization and nuclear matrix association. This mutation no longer repressed the HPV-11 upstream regulatory region-controlled reporter expression. However, a very small fraction of this mutant colocalized with E1 in the nucleus, perhaps by a piggyback mechanism, and was able to support transient replication. We propose that the hinge is critical for the diverse regulatory functions of the HPV-11 E2 protein during mRNA transcription and viral DNA replication.

Plan-view imaging of oxygen-induced reconstruction on Ag(110) surface. I. The possibility of imaging surface oxygen

Surface reconstruction on Ag(110) induced by oxygen adsorption was studied by the plan-view imaging technique of high-resolution electron microscopy (HREM). Systematic multislice simulations were carried out to find the optimal experimental conditions for imaging the surface oxygen. It was found theoretically that there exist a series of characteristic values of objective lens defoci and sample thicknesses under which the surface and the bulk can be imaged clearly and simultaneously. These optimal imaging conditions were used to interpret the experimental micrographs. While the basic features of the surface reconstruction of O/Ag(110) in the HREM images are consistent with those revealed by scanning tunnelling microscopy (STM), there are some new features that have not been reported with STM. These phenomena give some evidence to the existence of subsurface oxygen.